Continuously variable transmission drive pulley

ABSTRACT

A drive pulley for a CVT has a fixed sheave, a fixed sheave shaft fixedly connected to the fixed sheave, a movable sheave, a movable sheave shaft fixedly connected to the movable sheave, a spider and at least one centrifugal actuator. The fixed sheave shaft is disposed at least in part inside the movable sheave shaft. The movable sheave is disposed axially between the spider and the fixed sheave. A biasing member biases the movable sheave axially away from the fixed sheave. A torque transfer assembly is operatively connected to at least one of the fixed sheave and the movable sheave. The torque transfer assembly transfers torque between the fixed sheave and the movable sheave. The biasing member, the at least one centrifugal actuator and the torque transfer assembly are disposed radially outward of the fixed and movable sheave shafts.

CROSS-REFERENCE

The present application claims priority to U.S. Provisional PatentApplication No. 61/972,587, filed Mar. 31, 2014, the entirety of whichis incorporated herein by reference.

TECHNICAL FIELD

The present technology relates to drive pulleys for continuouslyvariable transmissions.

BACKGROUND

Conventional snowmobile powertrains incorporate a continuously variabletransmission (CVT) having a drive pulley that is operatively coupled tothe engine crankshaft and a driven pulley coupled to a driven shaft. Thedrive pulley transfers torque to the driven pulley via a drive beltlooped around both pulleys. Typically, the driven shaft is a transversejackshaft which drives the input member of a chain and sprocketreduction drive. The output of the reduction drive is coupled to one endof an axle on which are located the drive track drive sprocket wheels.

The drive pulley includes centrifugal actuators through which the driveratio of the drive pulley is varied progressively as a function of theengine speed. The centrifugal actuators are connected to a movablesheave of the drive pulley. The drive pulley also includes a fixedsheave which is axially fixed. The fixed sheave and the movable sheaveare rotatable together. The movable sheave is movable axially toward thefixed sheave by the action of the centrifugal actuators and away fromthe fixed sheave by a biasing spring. The centrifugal actuatorsgenerally consist of centrifugal weights in the form of adjusting arms.Each of the arms is connected to the movable sheave of the drive pulleyby a pin, and pivots outwards about its corresponding pin. As theypivot, the arms are in contact with corresponding rollers disposed on aspider fixed relative to the fixed sheave. When the adjusting arms pivotoutwards as a result of centrifugal force, they slide against theircorresponding roller and the axially movable sheave is pushed towardsthe fixed sheave.

Due to manufacturing tolerances and the type of connection used, it ispossible that the spider and movable sheave can rotate slightly relativeto one another during acceleration and deceleration of the drive pulley.As a result, the adjusting arms move slightly in a direction generallyparallel to an axis of rotation or their corresponding rollers. This issometimes referred to as backlash. This slight movement causes rubbingof the adjustable arms against their respective rollers and can resultin portions of the arms, the rollers or both to wear and form a flatportion or a recess. In the case of worn surfaces of the arms, the wayin which the movable sheave is moved by the arms in response to thespeed of rotation of the drive pulley is negatively affected. In thecase of worn surfaces of the rollers, it is possible that once the wornsurface of a roller makes contact with its corresponding arm, the rollerstops rolling, thereby further rubbing against the arm and exacerbatingthe problem.

Therefore, there is a need for a drive pulley that reduces or eliminatesrelative rotation between the spider and the movable sheave to helpprevent wear of the centrifugal actuators.

In some implementations, the fixed sheave is mounted on a fixed sheaveshaft, the movable sheave is mounted on a movable sheave shaft, and thespring biasing the movable sheave away from the fixed sheave is disposedradially between the fixed and movable sheave shafts. In order to reducefriction between the two shafts one or more low friction bushings aredisposed radially between the shafts. However, due to the presence ofthe spring radially between the two shafts, the maximum length of thebushings is limited, which can limit the life of the bushings.

Therefore, there is a need for a drive pulley having a connectionbetween the parts thereof that permit relatively easy displacement ofthe movable sheave relative to the fixed sheave in an axial direction,while allowing the length of the bushing(s) to be selected in order toprovide a desired durability to friction ratio.

SUMMARY

It is an object of the present to ameliorate at least some of theinconveniences present in the prior art.

According to an aspect of the present technology, there is provided adrive pulley for a continuously variable transmission having a fixedsheave, a fixed sheave shaft fixedly connected to the fixed sheave, amovable sheave axially movable relative to the fixed sheave, a movablesheave shaft fixedly connected to the movable sheave, the fixed sheaveshaft being disposed at least in part inside the movable sheave shaft, aspider axially fixed relative to the fixed sheave and rotationally fixedrelative to the movable sheave, the movable sheave being disposedaxially between the spider and the fixed sheave, a biasing memberbiasing the movable sheave axially away from the fixed sheave, thebiasing member being disposed radially outward of the fixed and movablesheave shafts, at least one centrifugal actuator including an armpivotally connected to one of the movable sheave and the spider, the armpivoting away from the one of the movable sheave and the spider as aspeed of rotation of the drive pulley increases, the arm pushing againstanother one of the movable sheave and the spider as the arm pivots awayfrom the one of the movable sheave and the spider, thereby moving themovable sheave axially toward the fixed sheave, the at least onecentrifugal actuator being disposed radially outward of the fixed andmovable sheave shafts, and a torque transfer assembly operativelyconnected to at least one of the fixed sheave and the movable sheave.The torque transfer assembly transfers torque between the fixed sheaveand the movable sheave. The torque transfer assembly is disposedradially outward of the fixed and movable sheave shafts.

In some implementations of the present technology, the torque transferassembly has at least one roller assembly. The at least one rollerassembly has a roller rotationally connected to one of the movablesheave and the spider and abutting another one of the movable sheave andthe spider. The roller rolls along the other one of the movable sheaveand the spider as the movable sheave moves axially. The roller transferstorque between the movable sheave and the fixed sheave. The roller isdisposed radially outward of the fixed and movable sheave shafts.

In some implementations of the present technology, the roller of the atleast one roller assembly is a first roller. The at least one rollerassembly also has a second roller rotationally connected to the one ofthe movable sheave and the spider and abutting the other one of themovable sheave and the spider. The second roller rolls along the otherone of the movable sheave and the spider as the movable sheave movesaxially. The second roller transfers torque between the movable sheaveand the fixed sheave. The second roller is disposed radially outward ofthe fixed and movable sheave shafts.

In some implementations of the present technology, for each of the atleast one roller assembly the first and second rollers are rotationallyconnected to the movable sheave.

In some implementations of the present technology, each of the at leastone roller assembly also has a radially extending axle connected to themovable sheave. For each of the at least one roller assembly the firstand second rollers are rotationally mounted to the axle and arerotatable about an axis of the axle.

In some implementations of the present technology, for each of the atleast one roller assembly the first and second rollers are slidablealong the axle.

In some implementations of the present technology, for each of the atleast one roller assembly: the spider defines a passage between a firstwall and a second wall, the first and second rollers are disposed in thepassage, the first roller abuts and rolls along the first wall and isspaced from the second wall, and the second roller abuts and rolls alongthe second wall and is spaced from the first wall.

In some implementations of the present technology, the at least onecentrifugal actuator is three centrifugal actuators disposed at 120degrees from each other. The at least one roller assembly is threeroller assemblies disposed at 120 degrees from each other. Thecentrifugal actuators and roller assemblies are arranged in analternating arrangement and are disposed at 60 degrees from each other.

In some implementations of the present technology, the arm of the atleast one centrifugal actuator abuts a roller rotationally connected tothe other one of the movable sheave and the spider.

In some implementations of the present technology, a damper connects thefixed sheave shaft to the spider. The damper transfers torque betweenthe fixed sheave shaft and the spider. The torque transfer assemblytransfers torque between the spider and the movable sheave.

In some implementations of the present technology, a first ring isconnected to the fixed sheave shaft and a second ring is connected tothe spider. The second ring is disposed axially between the first ringand the movable sheave. The damper is connected between the first andsecond rings and is disposed axially between the first and second rings.

In some implementations of the present technology, the damper is annularand is disposed radially outward of the fixed and movable sheave shafts.

In some implementations of the present technology, at least one bushingis disposed radially between the fixed and movable sheave shafts. The atleast one bushing abuts the fixed and movable sheave shaft. The at leastone bushing is axially fixed relative to the movable sheave shaft. Theat least one bushing is axially movable relative to the fixed sheaveshaft.

In some implementations of the present technology, the at least onebushing includes a first bushing disposed adjacent a first end of themovable sheave shaft and a second bushing disposed adjacent a second endof the movable sheave shaft.

In some implementations of the present technology, the first bushing,the second bushing, the movable sheave shaft and the fixed sheave shaftdefine an annular space therebetween. The annular space extendscontinuously from the first bushing to the second bushing.

In some implementations of the present technology, the first bushing isdisposed at least in part axially between ends of the biasing member.The first bushing is disposed radially between the biasing member andthe fixed sheave shaft. The second bushing is disposed axially betweenthe biasing member and the fixed sheave.

In some implementations of the present technology, the biasing member isdisposed at least in part inside the spider.

In some implementations of the present technology, a fixed spring seatabuts the spider and is axially fixed relative to the fixed sheaveshaft. A movable spring seat is connected to the movable sheave shaft.The movable spring seat is axially fixed relative to the movable sheaveshaft and is axially movable relative to the fixed sheave shaft. Thebiasing member is a coil spring having a first end abutting the fixedspring seat and a second end abutting the movable spring seat.

In some implementations of the present technology, the fixed spring seatis disposed axially between the movable spring seat and the fixedsheave.

According to another aspect of the present technology, there is provideda continuously variable transmission having the drive pulley accordingto any one of the above-mentioned implementation, a driven pulley and adrive belt looped around the fixed and movable sheaves. The drivenpulley has a fixed sheave and a movable sheave axially movable relativeto the fixed sheave.

According to another aspect of the present technology, there is provideda vehicle having a frame, a motor connected to the frame, the abovementioned continuously variable transmission, the drive pulley beingoperatively connected to and driven by the motor, a driven shaftconnected to and driven by the driven pulley, and at least one groundengaging member operatively connected to the driven shaft.

In some implementations of the present technology, the frame includes atunnel, and the at least one ground engaging member is a drive trackdisposed at least in part under the tunnel. The vehicle also has atleast one ski operatively connected to the frame, and a straddle seatdisposed above the tunnel.

Should there be contradictions between the definitions of terms providedin documents incorporated herein by reference and definitions of suchterms provided in the present application, the definitions in thepresent application prevail.

Implementations of the present technology each have at least one of theabove-mentioned object and/or aspects, but do not necessarily have allof them. It should be understood that some aspects of the presenttechnology that have resulted from attempting to attain theabove-mentioned object may not satisfy this object and/or may satisfyother objects not specifically recited herein.

Additional and/or alternative features, aspects, and advantages ofimplementations of the present technology will become apparent from thefollowing description, the accompanying drawings, and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present technology, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings, where:

FIG. 1 is a right perspective view of a snowmobile;

FIG. 2 is schematic representation of a perspective view, taken from afront, left side, of a powertrain of the snowmobile of FIG. 1;

FIG. 3 is a perspective view, taken from a bottom, front, left side of adrive pulley of a CVT of the powertrain of FIG. 2, with the drive pulleyin an opened position;

FIG. 4 is a left side elevation view of the drive pulley of FIG. 3, withthe drive pulley in an opened position;

FIG. 5 is a bottom plan view of the drive pulley of FIG. 3, with thedrive pulley in an opened position;

FIG. 6 is a cross-sectional view of the drive pulley of FIG. 3 takenthrough line 6-6 of FIG. 5, with the drive pulley in an opened position;

FIG. 7 is a bottom plan view of the drive pulley of FIG. 3, with thedrive pulley in a closed position;

FIG. 8 is a cross-sectional view of the drive pulley of FIG. 3 takenthrough line 8-8 of FIG. 7, with the drive pulley in a closed position;

FIG. 9 is a cross-sectional view of the drive pulley of FIG. 3 takenthrough line 9-9 of FIG. 5, with the drive pulley in an opened position;

FIG. 10 is a close-up view of a roller assembly of the drive pulley ofFIG. 3 taken through line 9-9 of FIG. 5;

FIG. 11 is a schematic illustration of an alternative implementation ofa roller assembly of the drive pulley of FIG. 3; and

FIG. 12 is a cross-sectional view of an alternative implementation ofthe drive pulley of FIG. 3, with the alternative implementation of thedrive pulley in an opened position.

DETAILED DESCRIPTION

A drive pulley for a continuously variable transmission (CVT) will bedescribed with respect to a snowmobile 10. However, it is contemplatedthat the drive pulley could be used in a CVT for other vehicles, suchas, but not limited to, on-road vehicles, off-road vehicles, amotorcycle, a scooter, a three-wheel road vehicle and an all-terrainvehicle (ATV). It is also contemplated that the CVT could be used indevices other than vehicles.

Turning now to FIG. 1, a snowmobile 10 includes a forward end 12 and arearward end 14 that are defined consistently with a forward traveldirection of the snowmobile 10. The snowmobile 10 includes a frame 16that includes a tunnel 18, an motor cradle portion 20 and a frontsuspension assembly portion 22. The tunnel 18 consists of one or morepieces of sheet metal arranged to form an inverted U-shape that isconnected at the front to the motor cradle portion 20 and extendsrearward therefrom along the longitudinal axis 23. A motor, which in thepresent implementation is an internal combustion engine 24(schematically illustrated in FIG. 1), is carried by the motor cradleportion 20 of the frame 16. The internal construction of the engine 24may be of any known type such as a two-stroke engine, a four-strokeengine or a diesel engine. It is contemplated that the engine 24 couldbe replaced by other types of motors, such as, but not limited to, anelectric motor or an electric/internal combustion hybrid engine. Twoskis 26 are positioned at the forward end 12 of the snowmobile 10 andare attached to the front suspension assembly portion 22 of the frame 16through a front suspension assembly 28. The front suspension assembly 28includes shock absorber assemblies 29, ski legs 30 and supporting arms32. Ball joints and steering rods (not shown) operatively connecting theskis 26 to a steering column 34. A steering device in the form ofhandlebar 36 is attached to the upper end of the steering column 34 toallow a driver to rotate the ski legs 30 and thus the skis 26, in orderto steer the snowmobile 10.

An endless drive track 38 is disposed generally under the tunnel 18 andis operatively connected to the engine 24 through a CVT 40(schematically illustrated by broken lines in FIG. 1) which will bedescribed in greater detail below. The endless drive track 38 is drivento run about a rear suspension assembly 42 for propulsion of thesnowmobile 10. The rear suspension assembly 42 includes a pair of sliderails 44 in sliding contact with the endless drive track 38. The rearsuspension assembly 42 also includes a plurality of shock absorbers 46which may further include coil springs (not shown) surrounding the shockabsorbers 46. Suspension arms 48 and 50 are provided to attach the sliderails 44 to the frame 16. A plurality of idler wheels 52 are alsoprovided in the rear suspension assembly 42. Other types and geometriesof rear suspension assemblies are also contemplated.

At the forward end 12 of the snowmobile 10, fairings 54 enclose theengine 24 and the CVT 40, thereby providing an external shell thatprotects the engine 24 and the CVT 40. The fairings 54 include a hoodand one or more side panels that can be opened to allow access to theengine 24 and the CVT 40 when this is required, for example, forinspection or maintenance of the engine 24 and/or the CVT 40. Awindshield 56 is connected to the fairings 54 near the forward end 12 ofthe snowmobile 10. Alternatively the windshield 56 could be connecteddirectly to the handlebar 36. The windshield 56 acts as a wind screen tolessen the force of the air on the driver while the snowmobile 10 ismoving forward.

A straddle-type seat 58 is positioned over the tunnel 18. Two footrests60 are positioned on opposite sides of the snowmobile 10 below the seat58 to accommodate the driver's feet.

FIG. 2 schematically illustrates a powertrain 62 of the snowmobile 10.The powertrain 62 includes the engine 24, the CVT 40 and a fixed ratioreduction drive 64. A throttle body 66 having a throttle valve 68therein is connected to air intake ports of the engine 24 to control theflow of air to the engine 24. It is contemplated that the throttle body66 could be replaced by a carburetor. The engine 24 drives a crankshaft(not shown) that rotates about a horizontally disposed axis that extendsgenerally transversely to the longitudinal axis 23 of the snowmobile 10.The crankshaft drives the CVT 40 for transmitting torque to the endlessdrive track 38 for propulsion of the snowmobile 10. The CVT 40 includesa drive pulley 100 coupled to the crankshaft to rotate with thecrankshaft of the engine 24 and a driven pulley 70 coupled to one end ofa transversely mounted jackshaft 72 that is supported on the frame 16through bearings. The opposite end of the transversely mounted jackshaft72 is connected to the input member of the reduction drive 64 and theoutput member of the reduction drive 64 is connected to a drive axle 74carrying sprocket wheels (not shown) that form a driving connection withthe drive track 38.

The drive pulley 100 of the CVT 40 includes a pair of opposedfrustoconical belt drive sheaves 102 and 104 between which a drive belt76 is located. The drive belt 76 is made of rubber, but it iscontemplated that it could be made of metal linkages or of a polymer.The drive pulley 100 will be described in greater detail below. Thedriven pulley 70 includes a pair of frustoconical belt drive sheaves 78and 80 between which the drive belt 76 is located. As can be seen, thedrive belt 76 is looped around both the drive pulley 100 and the drivenpulley 70. The torque being transmitted to the driven pulley 70 providesthe necessary clamping force on the drive belt 76 through its torquesensitive mechanical device in order to efficiently transfer torque tothe other powertrain components.

In the present implementation, the drive pulley 100 rotates at the samespeed as the crankshaft of the engine 24 whereas the speed of rotationof the transversely mounted jackshaft 72 is determined in accordancewith the instantaneous ratio of the CVT 40, and the drive axle 74rotates at a lower speed than the transversely mounted jackshaft 72because of the action of the reduction drive 64. The input member of thereduction drive 64 consists of a small sprocket connected to thetransversely mounted jackshaft 72 and coupled to drive an output memberconsisting of a larger sprocket connected to the drive axle 74 through adriving chain, all enclosed within the housing of the reduction drive64.

It is contemplated that the drive pulley 100 could be coupled to anengine shaft other than the crankshaft, such as an output shaft, acounterbalance shaft, or a power take-off shaft driven by the engine 24.The shaft driving the drive pulley 100 is therefore generally referredto herein as the driving shaft. Similarly, it is contemplated that thedriven pulley 70 could be coupled to a shaft other than the transverselymounted jackshaft 72, such as directly to the drive axle 74 or any othershaft operatively connected to the propulsion element of the vehicle(i.e. the drive track 38 in the case of the snowmobile 10). The shaftdriven by the driven pulley 70 is therefore generally referred to hereinas the driven shaft.

Turning now to FIGS. 3 to 9, the drive pulley 100 will be described inmore detail. As discussed above, the drive pulley 100 includes a pair ofopposed frustoconical belt drive sheaves 102 and 104. Both sheaves 102and 104 rotate together with the driving shaft. The sheave 102 is fixedin an axial direction relative to the driving shaft, and is thereforereferred to as the fixed sheave 102. The fixed sheave 102 is alsorotationally fixed relative to the driving shaft. The sheave 104 canmove toward or away from the fixed sheave 102 in the axial direction ofthe driving shaft in order to change the drive ratio of the CVT 40, andis therefore referred to as the movable sheave 104. As can be seen inFIG. 2, the fixed sheave 102 is disposed between the movable sheave 104and the engine 24.

The fixed sheave 102 is mounted on a fixed sheave shaft 106. The fixedsheave 102 is press-fitted on the fixed sheave shaft 106 such that thefixed sheave 102 rotates with the fixed sheave shaft 106. It iscontemplated that the fixed sheave 102 could be connected to the fixedsheave shaft 106 in other known manners to make the fixed sheave 102rotationally and axially fixed relative to the fixed sheave shaft 106.As can be seen in FIG. 6, the fixed sheave shaft 106 is hollow and has atapered hollow portion 108. The tapered hollow portion 108 receives theend of the driving shaft therein to transmit torque from the engine 24to the drive pulley 100. A fastener (not show) is inserted in the outerend (i.e. the left side with respect to FIG. 6) of the drive pulley 100,inside the fixed sheave shaft 106, and screwed into the end of thedriving shaft to prevent axial displacement of the fixed sheave shaft106 relative to the driving shaft. It is contemplated that the fixedsheave shaft 106 could be connected to the driving shaft in other knownmanners to make the fixed sheave shaft 106 rotationally and axiallyfixed relative to the driving shaft. It is also contemplated that thedriving shaft could be the fixed sheave shaft 106.

A cap 110 is taper-fitted in the outer end of the fixed sheave shaft106. The fastener used to connect the driving shaft to the fixed sheaveshaft 106 is also inserted through the cap 110 to connect the cap 110 tothe fixed sheave shaft 106. It is contemplated that the cap 110 could beconnected to the fixed sheave shaft 106 by other means. The radiallyouter portion of the cap 110 forms a ring 112. An annular rubber damper114 is connected to the ring 112. Another ring 116 is connected to therubber damper 114 such that the rubber damper 114 is disposed betweenthe rings 112, 116. As can be seen in FIG. 6, the rubber damper 114 andthe ring 116 are disposed radially outward of the fixed sheave shaft106. In the present implementation, the rubber damper 114 is vulcanizedto the rings 112, 116, but it is contemplated that they could beconnected to each other by other means such as by using an adhesive. Itis also contemplated that the damper 114 could be made of a materialother than rubber.

A spider 118 is disposed around the fixed sheave shaft 106 and axiallybetween the ring 116 and the movable sheave 104. The spider 118 isaxially fixed relative to the fixed sheave 102. As can be seen in FIGS.3 and 4, six apertures 120 are formed in the ring 112 and the damper114. The ring 116 has six corresponding apertures (not shown). Sixfasteners 122 (FIG. 4) are inserted through the apertures 120, throughthe ring 116 and into apertures 124 (FIG. 9) of the spider 118 to fastenthe ring 116 to the spider 118. As a result, torque is transferredbetween the fixed sheave shaft 106 and the spider 118 via the cap 110,the rubber damper 114 and the ring 116. The damper 114 dampens thetorque variations from the fixed sheave shaft 106 resulting from thecombustion events in the engine 24. The spider 118 therefore rotateswith the fixed sheave shaft 106.

As can be seen in FIG. 6, a movable sheave shaft 126 is disposed aroundthe fixed sheave shaft 106. The movable sheave 104 is press-fitted onthe movable sheave shaft 126 such that the movable sheave 104 rotatesand moves axially with the movable sheave shaft 126. It is contemplatedthat the movable sheave 104 could be connected to the movable sheaveshaft 126 in other known manners to make the movable sheave 104rotationally and axially fixed relative to the shaft 126. It is alsocontemplated that the movable sheave 104 and the movable sheave shaft126 could be integrally formed. Two bushings 128, 130 are disposedradially between and abut the movable sheave shaft 126 and the fixedsheave shaft 106. The bushings 128, 130 are disposed adjacent oppositeends of the movable sheave 126. Clips 132 disposed on either sides ofeach of the bushings 128, 130 prevent the bushing 128, 130 from movingaxially relative to the movable sheave shaft 126. As such, as themovable sheave 104, and therefore the movable sheave shaft 126, movesaxially relative to the fixed sheave shaft 106, the bushings 128, 130move axially together with the movable sheave shaft 126 and thereforemove axially relative to the fixed sheave shaft 106. The bushings 128,130 are made of a relatively low friction material thereby permittingeasy axial movement of the movable sheave shaft 126 along the fixedsheave shaft 106. Examples of low friction material include, but are notlimited to, brass and polyoxymethylene.

As can also be seen in FIG. 6, an annular space 134 is defined betweenthe bushings 128, 130, the movable sheave shaft 126 and the fixed sheaveshaft 106. As can be seen, no component of the drive pulley 100 isdisposed inside this space 134. As such, the annular space 134 extendscontinuously between the bushing 128, 130. Therefore, the constructionof the illustrated implementation allows the length of the bushings 128,130 in the axial direction to be selected in order to achieve a desiredbalance between the amount of friction generated by the bushings 128,130 in the axial direction and their resistance to wear. For example,the bushings 128, 130 could be longer than illustrated. It is alsocontemplated that a single bushing or more than two bushings could beprovided radially between the shafts 106, 126.

To transmit torque from the spider 118 to the movable sheave 104, atorque transfer assembly consisting of three roller assemblies 200connected to the movable sheave 104 is provided. The roller assemblies200 are disposed radially outward of the fixed and movable sheave shafts106, 126. The roller assemblies 200 engage the spider 118 so as topermit low friction axial displacement of the movable sheave 104relative to the spider 118 and to eliminate, or at least minimize,rotation of the movable sheave 104 relative to the spider 118. Asdescribed above, torque is transferred from the fixed sheave 106 to thespider 118 via the damper 114. The spider 118 engages the rollerassemblies 200 which transfer the torque to the movable sheave 104 withno, or very little, backlash. As such, the spider 118 is considered tobe rotationally fixed relative to the movable sheave 104. The threeroller assemblies 200 are disposed at 120 degrees from each other asbest seen in FIG. 9. It is contemplated that the roller assemblies 200could be connected to the spider 118 and engage the movable sheave 104.It is contemplated that in some implementations, the torque transferassembly could have more or less than three roller assemblies 200. Theroller assemblies 200 will be described in greater detail below.

As can be seen in FIG. 6, a biasing member in the form of a coil spring136 is disposed inside a cavity 138 defined radially between the movablesheave shaft 126 and the spider 118. At one end, the spring 136 abuts afixed spring seat 140. The spring 136 biases the fixed spring seat 140against a lip 142 of the spider 118, and therefore the fixed spring seat140 is axially fixed relative to the spider 118. At the opposite end,the spring 136 abuts a movable spring seat 144. The movable spring seat144 is held in place near the end of the movable sheave shaft 126 by thespring 136 and a C-clip 146 engaging the movable sheave shaft 126,thereby making the movable spring seat 144 axially fixed relative to themovable sheave shaft 126. As a result, this end of the spring 136 (i.e.the left end with respect to FIG. 6) and the movable spring seat 144move axially relative fixed sheave shaft 106 when the movable sheave 104and the movable sheave shaft 126 move axially. As the movable sheave 104and the movable sheave shaft 126 move axially toward the fixed sheave102, the spring 136 gets compressed as can be seen in FIG. 8. The spring136 biases the movable sheave 104 and the movable sheave shaft 126 awayfrom the fixed sheave 102 toward their position shown in FIG. 6. It iscontemplated that, in some implementations, the movable sheave 104 couldbe biased away from the fixed sheave 102 by mechanisms other than thespring 136. As can be seen in FIGS. 6 and 8, the bushing 128 is disposedaxially between the spring 136 and the fixed sheave 102 and the bushing130 is disposed in part axially between the ends of the spring 136.

As best seen in FIG. 3, the spider 118 has three arms 148 disposed at120 degrees from each other. Three rollers 150 are rotatably connectedto the three arms 148 of the spider 132. As shown in FIG. 9, each roller150 is disposed around an axle 152. Needle bearings 154 are disposedbetween the rollers 150 and the axles 152. The axles 152 are insertedinto apertures in their respective arms 148. Threaded fasteners 156fasten the axles 152 to their respective arms 148.

Three centrifugal actuators 158 are pivotally connected to threebrackets 160 formed by the movable sheave 104. Each roller 150 isaligned with a corresponding one of the centrifugal actuators 158. Sincethe spider 118 and the movable sheave 104 are rotationally fixedrelative to each other, the rollers 150 remain aligned with theircorresponding centrifugal actuators 158 when the shafts 106, 126 rotate.Also, since the roller assemblies 200 prevent backlash between thespider 118 and the movable sheave 104, wear of the centrifugal actuators158 that would have resulted from this backlash is prevented. As bestseen in FIG. 9, the centrifugal actuators 158 are disposed at 120degrees from each other. The centrifugal actuators 158 and the rollerassemblies 200 are arranged in an alternating arrangement and aredisposed at 60 degrees from each other. It is contemplated that therollers 150 could be pivotally connected to the brackets 160 and thatthe centrifugal actuators 158 could be connected to the arms 148 of thespider 118. It is also contemplated that there could be more or lessthan three centrifugal actuators 158, in which case there would be acorresponding number of arms 148, rollers 150 and brackets 160. It isalso contemplated that the rollers 150 could be omitted and replacedwith surfaces against which the centrifugal actuators 158 can slide asthey pivot.

In the present implementation, each centrifugal actuator 158 includes anarm 162 that pivots about an axle 164 connected to its respectivebracket 160 by a threaded fastener 166. The position of the arms 162relative to their axles 164 can be adjusted. It is contemplated that theposition of the arms 162 relative to their axles 164 could not beadjustable. Additional detail regarding centrifugal actuators of thetype of the centrifugal actuator 158 can be found in InternationalApplication Publication No. WO2013/032463 A2, published Mar. 7, 2013,the entirety of which is incorporated herein by reference.

A general operation of the drive pulley 100 will now be described. Whenthe driving shaft is not turning or is turning at low speeds, the drivepulley 100 is in the configuration shown in FIGS. 3 to 6. As can be seenin FIG. 6, under these conditions, the ends of the arms 162 are receivedin apertures 168 defined in the spider 118. As the speed of rotation ofthe driving shaft increases, the speed of rotation of the drive pulley100 increases with it. As a result, the arms 162 of the centrifugalactuators 158 pivot about their respective axles 164, thereby movingaway from the movable sheave 104. As the arms 162 of the centrifugalactuators 158 pivot, they push against the rollers 150 to move themovable sheave 104 and the movable sheave shaft 126 axially toward thefixed sheave 102. As the movable sheave 104 and the movable sheave shaft126 move axially toward the fixed sheave 102, the roller assemblies 200roll along surfaces of the spider 118 as will be described below. Whenthe speed of rotation of the driving shaft is high enough, the movablesheave 104 and the movable sheave shaft 126 move to the position shownin FIGS. 8 and 9, which is as close as the movable sheave 104 can be tothe fixed sheave 102. As the speed of rotation of the driving shaftdecreases, the centrifugal actuators 158 pivot back toward the movablesheave 104 and the spring 136 moves the movable sheave 104 and themovable sheave shaft 126 axially away from the fixed sheave 102. As themovable sheave 104 and the movable sheave shaft 126 move axially awayfrom the fixed sheave 102, the roller assemblies 200 roll along surfacesof the spider 118 as will be described below.

Turning now to FIGS. 9 and 10, one of the three roller assemblies 200will be described in more detail. As the three roller assemblies 200 areidentical, only one will be described. It is contemplated that at leastone of the roller assemblies 200 could differ from the others.

The roller assembly 200 has two rollers 202, 204 rotationally mounted ona radially extending axle 206. The rollers 202, 204 can slide along theaxle 206. The axle 206 is fastened by a threaded fastener 208 to abracket 210 formed by the movable sheave 104. The axis 212 of the axle206 intersects and is perpendicular to the axis of rotation 170 of thefixed sheave shaft 106. The rollers 202, 204 rotate about the axis 212.

As can be seen, the roller 204 is disposed radially outward of theroller 202. As can also be seen, the roller 204 is thicker, has a largerdiameter, and therefore is larger overall, than the roller 202. Therollers 202, 204 are made of a plastic such as, but not limited to,polyimide-based plastics. It is contemplated that the rollers 202, 204could be made of any other suitable material such as, but not limitedto, aluminum or other metals. In the present implementation, bothrollers 202, 204 are made of the same material, therefore since theroller 204 is bigger than the roller 202, the roller 204 is also heavierthan the roller 202. It is contemplated that the two rollers 202, 204could not be made of the same material and/or that the roller 204 couldbe smaller than the roller 202, but that the roller 204 would still beheavier than the roller 202.

As can be seen in FIG. 10, the roller 202 is partially tapered and theroller 204 is tapered. The roller 202 has an angled surface 214 thatextends toward the axis 212 as it extends away from the axis of rotation170 of the fixed sheave shaft 106 and a surface 216 that is parallel tothe axis 212. The angled surface 214 is disposed at an angle between 15and 45 degrees relative to the axis 212 and relative to the surface 216.As can be seen the angled surface 214 is disposed radially outward ofthe surface 216 with respect to the axis of rotation 170 of the fixedsheave shaft 106. The roller 204 has an angled surface 218 that extendstoward the axis 212 as it extends away from the axis of rotation 170 ofthe fixed sheave shaft 106. The angled surface 218 is disposed at anangle between 10 and 40 degrees relative to the axis 212.

For each roller assembly 200, the spider 118 defines a passage 220inside which the two rollers 202, 204 are received as can be seen inFIG. 10. The passage 220 is defined by walls 222 and 224 disposed oneither side of the rollers 202, 204. The roller 202 abuts the wall 222but is spaced from the wall 224 to prevent unwanted friction betweenroller 202 and wall 224 which would otherwise occur during operation.The angled surface 214 of the roller 202 abuts and angled surface 226 ofthe wall 222 defined by a projection 228 of the wall 222. The angledsurface 226 is disposed at the same angle relative to the axis 212 asthe angled surface 214. The surface 216 of the roller 202 abuts asurface 230 of the wall 222 that is parallel to the axis 212. The roller204 abuts the wall 224 but is spaced from the wall 222 to preventunwanted friction between roller 202 and wall 222 which would otherwiseoccur during operation. The angled surface 218 of the roller 204 abutsan angled surface 232 of the wall 224. The angled surface 232 isdisposed at the same angle relative to the axis 212 as the angledsurface 218. As can be seen in FIG. 10, the contact surface between theroller 204 and the wall 224 (i.e. the surface where the surface 218touches the surface 232) is larger than the contact surface between theroller 202 and the wall 222 (i.e. the surface where the surfaces 214,216 touch the surfaces 226, 230).

When the drive pulley 100 turns, the centrifugal forces on the rollers202, 204 push the rollers 202, 204 radially outwardly with respect tothe axis of rotation 170 of the fixed sheave shaft 106 along the axis212. As a result, the surface 214 of the roller 202 pushes against thesurface 226 of the wall 222, thereby pushing the spider 118 in thedirection of arrow A, and the surface 218 of the roller 204 pushesagainst the surface 232 of the wall 224, thereby pushing the spider 118in the direction of arrow B. As a result, the rollers 202, 204 eliminatebacklash between the spider 118 and the movable sheave 104 thuseliminating, or at least reducing, wear of the arms 162 and the rollers150 that would otherwise have resulted from rotation of the movablesheave 104 relative to the spider 118. At the position illustrated inFIG. 10, the rollers 202 and 204 are radially positioned along axis 212as far as they can move away from the axis of rotation 170. Although thecentrifugal forces acting upon each roller 202, 204 will increase withan increase of the rotation speed of the drive pulley 100, furtherradially outward movement of the roller 204 is prevented by the flatsurface 216 of the roller 202 that abuts the surface 230. At the sametime, the angled surface 226 prevents the roller 202 from any furtherradially outward movement along the axis 212. This relative placement ofrollers 202 and 204 with respect to their respective walls 222 and 224and the centrifugal actuators 158 is such that the arms 162 are alignedwith their respective rollers 150 when the rollers 202 and 204 are intheir maximum radially outward position along the axis 212 as shown inFIG. 10. As such, the roller 204 eliminates backlash when the spider 118applies torque to the movable sheave 104 in the direction indicated byarrow A (FIGS. 9 and 10), such as when the drive pulley 100 is turned inthe direction indicated by arrow A. The roller 202 eliminates backlashwhen the spider 118 applies torque in the direction indicated by arrow B(FIGS. 9 and 10), such as when the drive pulley 100 turns in thedirection indicated by arrow B to make the snowmobile move backward, orduring engine braking. Also, since the rollers 202, 204 can slide alongthe axle 206, as the rollers 202, 204 wear or undergo thermal expansionor contraction, they will nonetheless continue to make contact with thesurfaces 226, 232 and therefore continue to locate the actuators 158 inthe desired alignment with the rollers 150.

As described above, roller 204 has a greater mass than that of roller202. This result in the outer roller 204 generating more centrifugalforces than the inner roller 202 such that the influence of the roller202 is not great enough to cause the roller 204 to slide along thesurface 232 towards the axis 170. The centrifugal force applied by theroller 204 onto the surface 232 also counteracts the force applied fromthe belt 76 to the moveable sheave 104. During operation, once themoveable sheave 104 makes contact with the belt 76, the belt 76 appliesa torque in a direction (arrow B in FIG. 10) opposite to that of therotation of the moveable sheave 104 (arrow A in FIG. 10) and thuspressure between the roller 204 and the surface 232 increases andapplies a force to push the roller 204 radially inward towards the axis170. This force, and therefore the movement of the roller 204 toward theaxis 170, is countered by the centrifugal force acting on the roller204. As such, the mass of the roller 204 should be selected so as to belarge enough to ensure it does not move inwards due to the torque fromthe belt 76. It is contemplated that the mass, size and shape of therollers 202, 204 could differ from the description provided above, butwhile still having the outer roller 204 generate more centrifugal forcesthan the inner roller 202 and while still having the torque resultingfrom the centrifugal forces generated by the rollers 202, 204 besufficient to counter the effects of the torque applied by the belt 76in the direction of the arrow B (FIG. 10). By having the torqueresulting from the centrifugal forces generated by the rollers 202, 204being sufficient to counter the effects of the torque applied by thebelt 76 in the direction of the arrow B, rotation of the movable sheave104 relative to the spider 118 is prevented, thereby preventing wear onthe ramps 162 and rollers 154 which may otherwise result from suchrelative rotation. It is also contemplated that the outer roller 204could abut the wall 222 (and not the wall 224) and the inner roller 202could abut the wall 224 (and not the wall 222), in which case the mass,size and shape of the rollers 202, 204 should be selected such that theinner roller 202 generate more centrifugal forces than the outer roller204 and such that the inner roller 202 generates enough centrifugalforce to counter the effects of the torque applied by the belt 76 in thedirection of the arrow B (FIG. 10).

As can be seen by comparing FIGS. 5 and 6 to FIGS. 7 and 8, the rollers202, 204 roll along the walls 222, 224 respectively as the movablesheave 104 moves axially relative to the fixed sheave shaft 106. Sincethe rollers 202, 204 roll, torque is transferred between the spider 118and the movable sheave 104 while offering very little resistance to theaxial displacement of the movable sheave 104.

It is contemplated that the two rollers 202, 204 could be mounted ondifferent axles while still rolling along two walls 222, 224 of thespider 118, which may have to be disposed further apart. However, thetwo rollers 202, 204 of a roller assembly 200 should be sufficientlyclose to each other so as to be on a same side of a plane, such as theplane 234 (FIG. 9), containing the axis of rotation 170 of the fixedsheave shaft 106 and on a same side of another plane, such as the plane236 (FIG. 9) containing the axis of rotation 170 of the fixed sheaveshaft 106 and being perpendicular to the first plane. In other words,the two rollers 202, 204 of a roller assembly 200 should be at less than90 degrees from each other.

FIG. 11 schematically illustrates a roller assembly 300 that is analternative implementation of the roller assembly 200. The rollerassembly 300 has two rollers 302, 304. The roller 302 is rotationallymounted on an axle 306 and the roller 304 is rotationally mounted on anaxle 308. The rollers 302, 304 can slide along their respective axles306, 308. The axles 306, 308 are fastened by threaded fasteners 310 tobrackets 312 formed by the spider 118. The roller 302 is tapered and assuch has an angled surface 314. The roller 304 is also tapered and assuch has an angled surface 316.

The movable sheave 104 defines a wall 318 received between the rollers302, 304. The wall 318 has a projection 320 on a side thereof facing theroller 302 defining an angled surface 322 having the same angle as thesurface 314. The wall 318 has a projection 324 on a side thereof facingthe roller 304 defining an angled surface 326 having the same angle asthe surface 316. As can be seen, the projection 324 is more radiallyoutward than the projection 322.

When a drive pulley 100 having roller assemblies 300 turns, the surfaces314, 316 of the rollers 302, 304 push against their respective surfaces322, 326 of the wall 318, thereby holding the wall 318 between therollers 302, 304 and eliminating backlash. As the movable sheave 104moves axially relative to the fixed sheave 102, the rollers 302, 304roll along their respective sides of the wall 318, thereby offering verylittle resistance to the axial displacement of the movable sheave 104.

FIG. 12 illustrates a drive pulley 400 that is an alternativeimplementation of the drive pulley 100 described above. For simplicity,elements of the drive pulley 400 that are similar to those of the drivepulley 100 have been labelled with the same reference number and willnot be described again herein.

In the drive pulley 400, the cap 110, the damper 114 and the ring 116 ofthe drive pulley 100 have been replaced by a cap 402. The cap 402 has anouter peripheral flange 404. Fasteners 406 are inserted through theflange 404 and into the spider 118 to connect the cap 402 directly tothe spider 118.

Modifications and improvements to the above-described implementations ofthe present technology may become apparent to those skilled in the art.The foregoing description is intended to be exemplary rather thanlimiting. The scope of the present technology is therefore intended tobe limited solely by the scope of the appended claims.

1. A drive pulley for a continuously variable transmission comprising: afixed sheave; a fixed sheave shaft fixedly connected to the fixedsheave, a movable sheave axially movable relative to the fixed sheave; amovable sheave shaft fixedly connected to the movable sheave, the fixedsheave shaft being disposed at least in part inside the movable sheaveshaft; a spider axially fixed relative to the fixed sheave androtationally fixed relative to the movable sheave, the movable sheavebeing disposed axially between the spider and the fixed sheave; abiasing member biasing the movable sheave axially away from the fixedsheave, the biasing member being disposed radially outward of the fixedand movable sheave shafts; at least one centrifugal actuator includingan arm pivotally connected to one of the movable sheave and the spider,the arm pivoting away from the one of the movable sheave and the spideras a speed of rotation of the drive pulley increases, the arm pushingagainst another one of the movable sheave and the spider as the armpivots away from the one of the movable sheave and the spider, therebymoving the movable sheave axially toward the fixed sheave, the at leastone centrifugal actuator being disposed radially outward of the fixedand movable sheave shafts; and a torque transfer assembly operativelyconnected to at least one of the fixed sheave and the movable sheave,the torque transfer assembly transferring torque between the fixedsheave and the movable sheave, the torque transfer assembly beingdisposed radially outward of the fixed and movable sheave shafts, thetorque transfer assembly comprising at least one roller assembly, the atleast one roller assembly comprising: a roller rotationally connected toone of the movable sheave and the spider and abutting another one of themovable sheave and the spider, the roller rolling along the other one ofthe movable sheave and the spider as the movable sheave moves axially,the roller transferring torque between the movable sheave and the fixedsheave, and the roller being disposed radially outward of the fixed andmovable sheave shafts.
 2. (canceled)
 3. The drive pulley of claim 1,wherein the roller of the at least one roller assembly is a firstroller; and wherein the at least one roller assembly further comprises:a second roller rotationally connected to the one of the movable sheaveand the spider and abutting the other one of the movable sheave and thespider, the second roller rolling along the other one of the movablesheave and the spider as the movable sheave moves axially, the secondroller transferring torque between the movable sheave and the fixedsheave, and the second roller being disposed radially outward of thefixed and movable sheave shafts.
 4. The drive pulley of claim 3, whereinfor each of the at least one roller assembly the first and secondrollers are rotationally connected to the movable sheave.
 5. The drivepulley of claim 4, wherein each of the at least one roller assemblyfurther comprises a radially extending axle connected to the movablesheave; and wherein for each of the at least one roller assembly thefirst and second rollers are rotationally mounted to the axle and arerotatable about an axis of the axle.
 6. The drive pulley of claim 5,wherein for each of the at least one roller assembly the first andsecond rollers are slidable along the axle.
 7. The drive pulley of claim5, wherein for each of the at least one roller assembly: the spiderdefines a passage between a first wall and a second wall; the first andsecond rollers are disposed in the passage; the first roller abuts androlls along the first wall and is spaced from the second wall; and thesecond roller abuts and rolls along the second wall and is spaced fromthe first wall.
 8. The drive pulley of claim 1, wherein the at least onecentrifugal actuator is three centrifugal actuators disposed at 120degrees from each other; wherein the at least one roller assembly isthree roller assemblies disposed at 120 degrees from each other; andwherein the centrifugal actuators and roller assemblies are arranged inan alternating arrangement and are disposed at 60 degrees from eachother.
 9. The drive pulley of claim 1, wherein the arm of the at leastone centrifugal actuator abuts a roller rotationally connected to theother one of the movable sheave and the spider.
 10. The drive pulley ofclaim 1, further comprising a damper connecting the fixed sheave shaftto the spider, the damper transferring torque between the fixed sheaveshaft and the spider, and the torque transfer assembly transferringtorque between the spider and the movable sheave.
 11. The drive pulleyof claim 10, further comprising: a first ring connected to the fixedsheave shaft; and a second ring connected to the spider, the second ringbeing disposed axially between the first ring and the movable sheave;wherein the damper is connected between the first and second rings andis disposed axially between the first and second rings.
 12. The drivepulley of claim 11, wherein the damper is annular and is disposedradially outward of the fixed and movable sheave shafts.
 13. The drivepulley of claim 1, further comprising at least one bushing disposedradially between the fixed and movable sheave shafts, the at least onebushing abutting the fixed and movable sheave shafts, the at least onebushing being axially fixed relative to the movable sheave shaft, andthe at least one bushing being axially movable relative to the fixedsheave shaft.
 14. The drive pulley of claim 13, wherein the at least onebushing comprises a first bushing disposed adjacent a first end of themovable sheave shaft and a second bushing disposed adjacent a second endof the movable sheave shaft.
 15. The drive pulley of claim 14, whereinthe first bushing, the second bushing, the movable sheave shaft and thefixed sheave shaft define an annular space therebetween, the annularspace extending continuously from the first bushing to the secondbushing.
 16. The drive pulley of claim 14, wherein: the first bushing isdisposed at least in part axially between ends of the biasing member;the first bushing is disposed radially between the biasing member andthe fixed sheave shaft; and the second bushing is disposed axiallybetween the biasing member and the fixed sheave.
 17. The drive pulley ofclaim 1, wherein the biasing member is disposed at least in part insidethe spider.
 18. The drive pulley of claim 17, further comprising: afixed spring seat abutting the spider and being axially fixed relativeto the fixed sheave shaft; and a movable spring seat connected to themovable sheave shaft, the movable spring seat being axially fixedrelative to the movable sheave shaft and being axially movable relativeto the fixed sheave shaft; wherein the biasing member is a coil springhaving a first end abutting the fixed spring seat and a second endabutting the movable spring seat.
 19. The drive pulley of claim 18,wherein the fixed spring seat is disposed axially between the movablespring seat and the fixed sheave. 20.-22. (canceled)
 23. A drive pulleyfor a continuously variable transmission comprising: a fixed sheave; afixed sheave shaft fixedly connected to the fixed sheave, a movablesheave axially movable relative to the fixed sheave; a movable sheaveshaft fixedly connected to the movable sheave, the fixed sheave shaftbeing disposed at least in part inside the movable sheave shaft; aspider axially fixed relative to the fixed sheave and rotationally fixedrelative to the movable sheave, the movable sheave being disposedaxially between the spider and the fixed sheave; a biasing memberbiasing the movable sheave axially away from the fixed sheave, thebiasing member being disposed radially outward of the fixed and movablesheave shafts; at least one centrifugal actuator including an armpivotally connected to one of the movable sheave and the spider, the armpivoting away from the one of the movable sheave and the spider as aspeed of rotation of the drive pulley increases, the arm pushing againstanother one of the movable sheave and the spider as the arm pivots awayfrom the one of the movable sheave and the spider, thereby moving themovable sheave axially toward the fixed sheave, the at least onecentrifugal actuator being disposed radially outward of the fixed andmovable sheave shafts; a torque transfer assembly operatively connectedto at least one of the fixed sheave and the movable sheave, the torquetransfer assembly transferring torque between the fixed sheave and themovable sheave, the torque transfer assembly being disposed radiallyoutward of the fixed and movable sheave shafts; a first bushing disposedradially between the fixed and movable sheave shafts, the first bushingabutting the fixed and movable sheave shafts, the first bushing beingaxially fixed relative to the movable sheave shaft, and the firstbushing being axially movable relative to the fixed sheave shaft; and asecond bushing disposed radially between the fixed and movable sheaveshafts, the second bushing abutting the fixed and movable sheave shafts,the second bushing being axially fixed relative to the movable sheaveshaft, and the second bushing being axially movable relative to thefixed sheave shaft, the first bushing, the second bushing, the movablesheave shaft and the fixed sheave shaft defining an annular spacetherebetween, the annular space extending continuously from the firstbushing to the second bushing.
 24. The drive pulley of claim 23, whereinthe first bushing is disposed adjacent a first end of the movable sheaveshaft and the second bushing is disposed adjacent a second end of themovable sheave shaft.
 25. The drive pulley of claim 23, wherein the armof the at least one centrifugal actuator abuts a roller rotationallyconnected to the other one of the movable sheave and the spider.
 26. Thedrive pulley of claim 23, further comprising a damper connecting thefixed sheave shaft to the spider, the damper transferring torque betweenthe fixed sheave shaft and the spider, and the torque transfer assemblytransferring torque between the spider and the movable sheave.
 27. Thedrive pulley of claim 26, further comprising: a first ring connected tothe fixed sheave shaft; and a second ring connected to the spider, thesecond ring being disposed axially between the first ring and themovable sheave; wherein the damper is connected between the first andsecond rings and is disposed axially between the first and second rings.28. The drive pulley of claim 27, wherein the damper is annular and isdisposed radially outward of the fixed and movable sheave shafts. 29.The drive pulley of claim 24, wherein: the first bushing is disposed atleast in part axially between ends of the biasing member; the firstbushing is disposed radially between the biasing member and the fixedsheave shaft; and the second bushing is disposed axially between thebiasing member and the fixed sheave.
 30. The drive pulley of claim 23,wherein the biasing member is disposed at least in part inside thespider.
 31. The drive pulley of claim 30, further comprising: a fixedspring seat abutting the spider and being axially fixed relative to thefixed sheave shaft; and a movable spring seat connected to the movablesheave shaft, the movable spring seat being axially fixed relative tothe movable sheave shaft and being axially movable relative to the fixedsheave shaft; wherein the biasing member is a coil spring having a firstend abutting the fixed spring seat and a second end abutting the movablespring seat.
 32. The drive pulley of claim 31, wherein the fixed springseat is disposed axially between the movable spring seat and the fixedsheave. 33.-35. (canceled)